• Journal of Appropriate Technology
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• v.7 no.2
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• pp.127-135
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• 2021

To respond to the threat of global warming, countries around the world are promoting the spread of renewable energy and reduction of carbon emissions. In accordance with the United Nation's Sustainable Development Goal to combat climate change and its impacts, global automakers are pushing for a full transition to electric vehicles within the next 10 years. Electric vehicles can be a useful means for reducing carbon emissions, but in order to reduce carbon generated in the stage of producing electricity for charging, a power generation system using eco-friendly renewable energy is required. In this study, we propose a smart electric mobility operating system integrated with off-grid solar power plants established in Tanzania, Africa. By applying smart monitoring and communication functions based on Arduino-based computing devices, information such as remaining battery capacity, battery status, location, speed, altitude, and road conditions of an electric vehicle or electric motorcycle is monitored. In addition, we present a scenario that communicates with the surrounding independent solar power plant infrastructure to predict the drivable distance and optimize the charging schedule and route to the destination. The feasibility of the proposed system was verified through test runs of electric motorcycles. In considering local environmental characteristics in Tanzania for the operation of the electric mobility system, factors such as eco-friendliness, economic feasibility, ease of operation, and compatibility should be weighed. The smart electric mobility operating system proposed in this study can be an important basis for implementing the SDGs' climate change response.

• Journal of Korean Society of Disaster and Security
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• v.14 no.4
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• pp.47-60
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• 2021

Recently, as the occurrence frequency of sudden floods due to climate variability increased, the damage of aging chuteway slabs of spillway are on the rise. Accordingly, a wide array of field survey, hydraulic experiment and numerical simulation have been conducted to find the cause of damage on chuteway slabs. However, these studies generally reviewed the flow characteristics and distribution of pressure on chuteway slabs. Therefore the derivation of damage on chuteway slabs was relatively insufficient in the literature. In this study, the cavitation erosion and hydraulic jacking were assumed to be the causes of damage on chuteway slabs, and the phenomena were reproduced using 3D numerical models, FLOW-3D and COMSOL Multiphysics. In addition, the cavitation index was calculated and the von Mises stress by uplift pressure distribution was compared with tensile and bending strength of concrete to evaluate the possibility of cavitation erosion and hydraulic jacking. As a result of numerical simulation on cavitation erosion and hydraulic jacking under various flow conditions with complete opening gate, the cavitation index in the downstream of spillway was less than 0.3, and the von Mises stress on concrete was 4.6 to 5.0 MPa. When von Mises stress was compared with tensile and bending strength of concrete, the fatigue failure caused by continuous pressure fluctuation occurred on chuteway slabs. Therefore, the cavitation erosion and hydraulic jacking caused by high speed flow were one of the main causes of damage to the chuteway slabs in spillway. However, this study has limitations in that the various shape conditions of damage(cavity and crack) and flow conditions were not considered and Fluid-Structure Interaction (FSI) was not simulated. If these limitations are supplemented and reviewed, it is expected to derive more efficient utilization of the maintenance plan on spillway in the future.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.2
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• pp.1-22
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• 2022

The modification effects of street trees on outdoor thermal comfort in summertime according to tree planting types and road direction were analyzed using a computer simulation program, ENVI-met. With trees, the air temperature and wind speed decreased, and the relative humidity increased. In the case of mean radiant temperature (T_mrt) and human thermal sensation, physiological equivalent temperature (PET) and universal thermal climate index (UTCI), there was a decrease during the daytime. The greatest change among the meteorological factors by trees happened in Tmrt, and PET and UTCI showed similar patterns with T_mrt·The most effective tree planting type on thermal comfort modification was low tree height, wide tree crown, high leaf area index, and narrow planting interval (LWDN). T_mrt, PET and UTCI showed a large difference depending on shadow patterns of buildings and trees according to solar altitude and azimuth angles, and building locations. When the building shade areas increased, the thermal modification effect by trees decreased. In particular, results on the east and west sidewalks showed a large deviation over time. When applying the LWDN, the northwest, west and southwest sidewalks showed a significant reduction of 8.6-12.3℃ PET and 4.2-4.5℃ UTCI at 10:00, and the northeast, east and southeast sidewalks showed 8.1-11.8℃ PET and 4.4-5.0℃ UTCI at 16:00. On the other hand, when the least effective type (high tree height, narrow tree crown, low leaf area index, and wide planting interval) was applied, the maximum reduction was up to 1.8℃ PET and 0.9℃ UTCI on the eastern sidewalks, and up to 3.0℃ PET and 0.9℃ UTCI on the western ones. In addition, the difference in modification effects on T_mrt, PET and UTCI between the tree planting types was not significant when the tree effects were reduced by the effects of buildings. These results can be used as basic data to make the most appropriate street tree planting model for thermal comfort improvement in urban areas in summer.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.965-972
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• 2022

This is a basic study to establish marine activity criteria based on the seakeeping performance of less than 10-tons fishing vessels. These vessels account for approximately 95% of Korea's currently registered fishing vessels, and accidents and loss of life are also occurring during marine activities such as navigation, and fishing. Accordingly, the Ministry of Oceans and Fisheries has set a regulation of vessel traf ic control to restrict the operation of fishing vessels when the high seas watch takes effect, but it is applied equally without criteria according to the ship ton level and wave height; therefore, many differences may exist in ship fluctuations. Because the fluctuation of the ship owing to the wave height can be a factor in marine accidents by reducing the sense of boarding and performance of equipment, the seakeeping performance must be reviewed during waves to secure safe marine activities such as navigation and fishing. However, the review for the fishing vessel of established marine activity criteria based on the seakeeping performance is insufficient. Accordingly, the seakeeping performance was evaluated for a 10-ton class (G/T 9.77 tons) fishing vessel in Korea, and the level of marine activity according to the significant wave height and ship speed was interpreted by applying the operation and survival of the established seakeeping performance criteria. The analysis results indicated that the roll of the ship exceeded the operation criteria from 0.4m and the survival criteria from 2.2m. The pitch of the ship exceeded the operation criteria from 1.7m and did not exceed the survival criteria until 3.0m. However, the rolling exceeding the survival criteria from 2.2m may not be safe. Therefore, fishing vessels with less than 10-tons can leave before the high seas watch takes effect. However, they did not satisfy the criteria for evaluating the performance of the sea in relation to marine activities. Although this study was limitedly evaluated for 10-ton fishing vessels, it is expected to be of great help in preparing marine activity criteria.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.3
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• pp.127-143
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• 2022

Recently, many attempts to run numerical ocean models in cloud computing environments have been tried actively. A cloud computing environment can be an effective means to implement numerical ocean models requiring a large-scale resource or quickly preparing modeling environment for global or large-scale grids. Many commercial and private cloud computing systems provide technologies such as virtualization, high-performance CPUs and instances, ether-net based high-performance-networking, and remote direct memory access for High Performance Computing (HPC). These new features facilitate ocean modeling experimentation on commercial cloud computing systems. Many scientists and engineers expect cloud computing to become mainstream in the near future. Analysis of the performance and features of commercial cloud services for numerical modeling is essential in order to select appropriate systems as this can help to minimize execution time and the amount of resources utilized. The effect of cache memory is large in the processing structure of the ocean numerical model, which processes input/output of data in a multidimensional array structure, and the speed of the network is important due to the communication characteristics through which a large amount of data moves. In this study, the performance of the Regional Ocean Modeling System (ROMS), the High Performance Linpack (HPL) benchmarking software package, and STREAM, the memory benchmark were evaluated and compared on commercial cloud systems to provide information for the transition of other ocean models into cloud computing. Through analysis of actual performance data and configuration settings obtained from virtualization-based commercial clouds, we evaluated the efficiency of the computer resources for the various model grid sizes in the virtualization-based cloud systems. We found that cache hierarchy and capacity are crucial in the performance of ROMS using huge memory. The memory latency time is also important in the performance. Increasing the number of cores to reduce the running time for numerical modeling is more effective with large grid sizes than with small grid sizes. Our analysis results will be helpful as a reference for constructing the best computing system in the cloud to minimize time and cost for numerical ocean modeling.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.746-752
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• 2022

Kiribati, a South Pacific island, and its surrounding countries are gradually submerging to rising sea levels. The sea level continues to change according to the degree of thermal expansion of glaciers and seawater that decreases with increase in temperature. Global warming affects both the amount and volume of seawater, thus increasing sea level. Tidal phenomena occur twice a day to the attraction of celestial bodies such as the moon and the sun. The moon changes the angle of orbiting surface with the Earth equator every 18.6 years, and the magnitude of the tidal force changes depending on the distance between the Earth equator and the moon orbital surface. The University of Hawaii Sea Level Center selected Tarawa, Christmas, Kanton of Kiribati,, Lautoka, Suva of Fiji,Funafuti of Tuvalu, Nuk1u'alofa of Tonga, and Port Vila of Vanuatu. When comparing tide levels for each year for 19 years, the focus was on checking the change in sleep to Tide levels, and rising sea levels was the effect of Tide levels. The highest astronomical tides (HAT) and lowest astronomical tides (LAT) were identified as Tarawa 297.0, 50.8 cm, Christmas 123.8, 19.9 cm, Kanton 173.7, 39.9 cm, Lautoka 240.7, 11.3 cm, Funafuti 328.6, 98.4 cm, Nuk1u'alofa 188.8, 15.5 cm, Port Vila 161.5, -0.5cm, respectively. The Sea level rising speed was Tarawa 3.1 mm/year, Christmas -1.0 mm/year, Kanton 1.6 mm/year, Lautoka 3.1 mm/year, Suva 7.4 mm/year, Funafuti 1.4 mm/year, Nuk1u'alofa 4.2 mm/year, and Port Vila -1.2 mm/year, respectively

• Journal of the Korean Society of Tobacco Science
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• v.24 no.1
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• pp.67-73
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• 2002

In light of addressing consumer health concern, coping with anti-tobacco movement, and promoting new product, tobacco industry is actively pursuing to make a new generation of cigarettes with low tar and nicotine deliveries, and less harmful substances. Low tar and low nicotine cigarettes increases their market shares dramatically world wide, especially in KT&G, multinational tobacco companies, EU countries, even in China regulated by CNTC to set up yearly target to lower tar and nicotine deliveries. On the other hand, to design a new cigarette with reduced harmful substances begins to gain speed. The "modified Hoffmann list" publishes thirty plus substances in tobacco leaf and main smoke stream, which is the prime suspect causing health problems. Various ways and means are developed to reduce such components including new tobacco breeds, new curing method, tobacco leaf treatment before processing, selected filtration system, innovated casing system to reduce free radicals, as well as some non conventional cigarette products. In TSRC held this year, the main topic is related to reduce tobacco specific nitrosamines in tobacco leaf. The new generation of cigarette is in the horizon. It still needs a lot help to produce commercial products with satisfied taste and aroma characters. The flavor industry is not regulated by many governments demanding which ingredients might or might not be for tobacco use. However, most of the cigarette companies self impose a list of ingredients to guide flavor suppliers to design flavors. Unfortunately, the number of ingredients in those lists is getting shorter every year. It is understandable that the health is not the only reason. Some cigarette companies are playing safe to protect the company from potential lawsuit, while others are just copying from their competitors. Moreover, it is obvious that it needs more assistance from casings and flavors to design new generation of cigarettes with missing certain flavor components in tobacco leaf and main smoke stream. These flavor components are either non-existed or at lower level at new form of cured tobacco leaf or filtered in the main smoke stream along with reduced harmful substances. The use of carbon filters and other selected filtration system poses another tough task for flavor system design. Specific flavor components are missing from the smoke analysis data, which brings a notion of "carbon taste" and "dryness" of mouth feel. It is ever more demanded by cigarette industry to flavor suppliers to produce flavors as body enhancer, tobacco notes, salivating agents, harshness reducer, and various of aromatic notes provided they are safe to use. Another trend is that water based flavor or flavor with reduced ethanol as solvent is gaining popularity. It is preferred by some cigarette companies that the flavor is compounded with all natural ingredients or all ingredients should he GMO free. The new generation of cigarettes demands many ways of new thinking process. It is also vital for tobacco industry. It reflects the real needs for the consumers that the cigarette product should be safe to use as well as bearing the taste and aroma characters smokers always enjoyed. An effective tobacco flavor system is definitely a part of the equation. The global trend of tobacco industry is like trends of any other industries lead by consumer needs, benefited with new technology availability, affected by the global economy, and subjected for various rules and regulations. Anti-tobacco organizations and media exceptionally scrutinize cigarette, as a legal commercial product. Cigarette is probably the most studied commercial product for its composition, structure, deliveries, effects, as well as its new developmental trend. Therefore, any new trend of cigarette development would be within these boundaries. This paper is trying to point out what it would be like for tobacco industry in the next few yews and what concerns the tobacco industry. It focuses mostly on the efforts to produce safer cigarettes. It is such a vital task for the tobacco industry and its affiliate industries such as cigarette papers, filters, flavors, and other materials. The facts and knowledge presented in this paper might be well known for the public. Some of the comments and predictions are very much personal opinion for a further discussion.

• Journal of Service Research and Studies
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• v.12 no.2
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• pp.135-151
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• 2022

This study was conducted on a servicism basis as a study to build the management wisdom of Korea as an asset of human society. The case of the founding and development of the Republic of Korea, which developed into one of the world's leading powers with unprecedented rapid growth despite the devastating three-year war immediately after its founding, is an important subject of study. This study conducted a macroscopic analysis. In the process of carrying out the founding activities, it was confirmed that the original idea inherent in Koreans was the Taegeuk idea of the National Flag. The founders of the Republic of Korea consciously or unconsciously adopted the Taegeuk ideology as the founding ideology. It can be said that the Taegeuk ideology has led to greater success because it is based on the service philosophy, which is the common truth of mankind. In this study, the process of preparing for the founding of the Republic of Korea, which was founded by accepting a new maritime civilization from a country with a long continental civilization, the process of national foundation, and the process of operating the country after its founding were analyzed as a whole. In particular, it discovered the excellent wisdom of the founders who appropriately utilized the strengths of continental and maritime civilizations in necessary situations, and confirmed that the dynamic operating model of development through fierce competition between the two opponents was a success factor for high-speed national development. It requires great wisdom for Koreans with diverse ideological backgrounds and unique personalities to unite to establish and run a nation. This is because fierce competition and cooperation must be carried out at the same time. The great wisdom of the founding of the Republic of Korea was able to be demonstrated because the Taegeuk ideology was acting as a common basic ideology for Koreans. Taegeuk ideology, the source of wisdom that Korea has developed under constant tension, can be capitalized as human wisdom, and additional case studies are needed.

• Journal of Service Research and Studies
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• v.12 no.2
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• pp.65-79
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• 2022

Non-face-to-face classes continue due to Covid-19. There have been e-learning classes since the past, but the difference is that the current non-face-to-face classes are blended classes that combine real-time and recording classes or combine face-to-face and non-face classes. It is also characterized by being able to self-filmed or choose various lecture platforms in a place other than a dedicated studio. The advantages of non-face-to-face classes can be learned beyond time and space, and repetitive viewing and learning speed can be adjusted. Greening classes have no time and place constraints, and real-time classes have the advantage of high communication effects with learners. Evaluating whether non-face-to-face classes provide sufficient quality compared to face-to-face classes or e-learning will be necessary if branded classes are considered for post Covid. In this paper, for the evaluation of the service quality of non-face-to-face classes, the essential attributes desired by the instructors were derived from the viewpoint of Kano quality attributes and a quality improvement plan was proposed. After expressing the degree of functions that non-face-to-face classes should have on the X-axis and the satisfaction of learners on the Y-axis, 23 quality attributes were classified into 6 quality dimensions. In addition, satisfaction coefficient, dissatisfaction coefficient, and customer satisfaction improvement index were derived. As a result, 50% of learners were satisfied with non-face-to-face classes, but the preference was slightly higher than satisfaction, suggesting the sustainability of non-face-to-face classes. In terms of the customer satisfaction improvement index, the ranking of attributes with the largest increase in satisfaction when improving class quality was as follows. Professors' quick answers to learners' questions, content that can fully explain the subject, what the professor explains easily, develop high-quality content that can be learned on mobile phones, fairness of attendance checks, and real-time classes should start on time.

• Journal of Intelligence and Information Systems
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• v.29 no.1
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• pp.249-263
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• 2023

Collaborative Filtering, a representative recommendation system methodology, consists of two approaches: neighbor methods and latent factor models. Among these, the latent factor model using matrix factorization decomposes the user-item interaction matrix into two lower-dimensional rectangular matrices, predicting the item's rating through the product of these matrices. Due to the factor vectors inferred from rating patterns capturing user and item characteristics, this method is superior in scalability, accuracy, and flexibility compared to neighbor-based methods. However, it has a fundamental drawback: the need to reflect the diversity of preferences of different individuals for items with no ratings. This limitation leads to repetitive and inaccurate recommendations. The Adaptive Deep Latent Factor Model (ADLFM) was developed to address this issue. This model adaptively learns the preferences for each item by using the item description, which provides a detailed summary and explanation of the item. ADLFM takes in item description as input, calculates latent vectors of the user and item, and presents a method that can reflect personal diversity using an attention score. However, due to the requirement of a dataset that includes item descriptions, the domain that can apply ADLFM is limited, resulting in generalization limitations. This study proposes a Generalized Adaptive Deep Latent Factor Recommendation Model, G-ADLFRM, to improve the limitations of ADLFM. Firstly, we use item ID, commonly used in recommendation systems, as input instead of the item description. Additionally, we apply improved deep learning model structures such as Self-Attention, Multi-head Attention, and Multi-Conv1D. We conducted experiments on various datasets with input and model structure changes. The results showed that when only the input was changed, MAE increased slightly compared to ADLFM due to accompanying information loss, resulting in decreased recommendation performance. However, the average learning speed per epoch significantly improved as the amount of information to be processed decreased. When both the input and the model structure were changed, the best-performing Multi-Conv1d structure showed similar performance to ADLFM, sufficiently counteracting the information loss caused by the input change. We conclude that G-ADLFRM is a new, lightweight, and generalizable model that maintains the performance of the existing ADLFM while enabling fast learning and inference.